Aim: The consumption of added sugars containing fructose has increased dramatically. Various studies have revealed that added sugar consumption may be involved in the pathogenesis of cardiovascular, metabolic, and neurocognitive disorders by triggering subclinical inflammation. The imbalance in the kynurenine pathway metabolites may be associated with inflammation and oxidative stress. This study aims to investigate the effect of high-fructose corn syrup-55 (HFCS-55), invert sugar and sucrose intervention on the kynurenine pathway metabolite levels (tryptophan, kynurenine, 3-hydroxykynurenine, 3-hydroxyanthranilic acid, quinolinic acid, and kynurenic acid) in Wistar rats. Material and Methods: Twenty-four Wistar male rats (8-12 weeks old, weighing 300-350 g) were included in the study. After one week of conditioning, the animals were randomly divided into four groups: chow diet and tap water (control, n = 6), chow diet and tap water including 10% HFCS-55 (55% sucrose, 45% glucose), chow diet and tap water including 10% sucrose, chow diet and tap water including 10% invert sugar (33% sucrose, 66% glucose and fructose). At the end of the 3-month experimental period, serum kynurenine metabolites levels were measured by tandem mass spectrometry. Results: Serum kynurenine levels and kynurenine/tryptophan ratio were significantly higher (p<0.05) and serum kynurenic acid levels were significantly lower (p<0.05) in rats fed with HFCS, sucrose and invert sugar compared to the control group. Conclusion: Our findings suggest that consumption of added sugar may lead to an imbalance in the kynurenine pathway metabolites. The altered kynurenine metabolism may trigger inflammation and oxidative damage, and may predispose to chronic diseases.